AU608626B2

AU608626B2 - A cylinder-piston device

Info

Publication number: AU608626B2
Application number: AU18918/88A
Authority: AU
Inventors: Rolf Mintgen
Original assignee: Stabilus GmbH
Current assignee: Stabilus GmbH
Priority date: 1987-07-23
Filing date: 1988-07-08
Publication date: 1991-04-11
Anticipated expiration: 2008-07-08
Also published as: DE3869506D1; EP0300351B1; BR8803670A; JPS6440763A; US4896587A; DE3724370A1; ES2031183T3; AU1891888A; EP0300351A1

Description

By: I~ Registered Patent Atrorney To: The Commissioner of Patents -COMMONWEALTH OF AUSTRALIA Ti COMMONWEALTH OF AUSTRALIA Patent Act 1952 COMt4P LE TE SP EC IF I CA TIO N

(ORIGINAL)

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C' C) C' C (0 0 00 Complete Specification Lodged Accepted Tfiis document Contains the aomen dnen ts 111ade u nd-r 'kctioi .19 and i~s curreet for Published 23 July 1987 Priority Related Art Name of Applicant Address of Applicant STABILUS GMB11 :Wallersheiner Weg 100 D-5400 Koblenz-Neuendorf Federal Republic of Germany 00 Actual Inventor/s Address for Service Rolf mintgen F.B. RICE CO., Patent Attorneys, 28A Montague Street, BALMAJ2N 2041.

Complete Specification for the invention entitled: A CYLINDR-PISTON DEVICE The following statement is a full description of this invention including the best method of performing it known to us/ind:- Signed... Status...Managing...Dir ec.tr..Deputy....Man.aging. Director Stabilus GmbI DeclarantsName Alfred Klein Roland Ulbricht D e c la ra n t's N a E B. RICE CO PATENT ATTORNEYS This form is suitable for any type of Patent Application. No legalisation required.

BACKGROUND OF THE INVENTION In cylinder-piston devices in which a pressurized fluid is contained within the container there is a problem of reliably sealing the piston rod with respect to the end of So the container through which the piston rod passes.

coo0 0 0 o This invention relates to an improvement of the sealing 0 0 O, means between the container and the piston rod in such a oo o 0o cylinder-piston device.

0 00 OQOOO IQ 0on STATEMENT OF THE PRIOR ART 0 00 00 0 0 0 0 a 0 In German Offenlegungsschrift 35 03 537 a scaling 0 0 o chamber is established adjacent to a piston rod guiding rin 00 0 between an axially outer sealing ring and an axially inner 0 0 Ssealing ring. This sealing chamber is filled with a liquid.

The axially inner sealing ring is axially biased towards the axially outer sealing ring by a mechanical spring supported by a supporting bulge of the container. When the liquid within the sealing chamber slowly escapes, the mechanical spring maintains the pressure of the liquid within the sealing chamber. So, the sealing function is maintained during an extended lifetime.

2- OBJECT OF THE INVENTION It is a primary object of the present invention to provide a cylinder piston unit of simplified and economic dosign, in which the pressure within a sealing chamber is maintained over an extended lifetime. More particularly mec c SE chanical springs for maintaining the pressure within the I sealing chamber should be avoided.

c soMMARY OF s T.e INgVEcsTIi oo A cylinder-piston device comprises a cylindrical tainer having an axis and two ends and defining a cavity 000 therein. Piston rod guiding means are provided adjacent to at least a first one of said two ends. A piston rod member c cc is guided by the piston rod guiding means inwards and outwards of the container along the axis thereof. Sealing mean are provided adjacent to the piston rod guiding means. These j| 20 sealing means comprise an axially outer sealing unit and an axially inner sealing unit. A sealing chamber is defined axially between the axially outer and the axially inner sealing units. Both the axially outer and the axially inner sealing units comprise a respective sealing ring member.

These sealing ring members are in sealing engagement with both an internal circumferential face of the container and an external circumferential face of the piston rod member.

3 1 ,e I_ ;I I i A working chamber is defined axially between the axially inner sealing unit and the second end of the container. The working chamber contains a volume of pressurized fluid. Each of said sealing ring members has a radially outer sealing lip sealingly engaging said internal circumferential fac, and a.radially inner. sealing lip sealingly engaging said external circumferential face. Respective sealing lips of ,o the sealing ring members extend in opposite axial direction.: Q0 0 0o towards said sealing chamber. The sealing chamber receives a volume of pressurized gas. The pressure of this volume of pressurized gas within the sealing chamber exceeds the pressure of the pressurized fluid within said working charb or.

Xn the cylinder-piston device of this invention the 7 scaling effect of both sealing ring members is independcn:.

of the pressure within the working chamber. The pressure within thu sealing chamber is at least after manufacturing and during an early period of the lifetime greater than thu pressure within the working chamber. This may change later, However, even after the pressure difference has disappeared, a high sealing action is still warranted.

The pressure of the gas within the sealing chamber acts radially onto the sealing lips and urges the sealing lips radially against the respective circumferential faces. Such, the escape of pressurized gas from the sealing chamber is prevented in both axial directions. Simultaneously, the escape of gas from the working chamber towards the sealing chamber is prevented as long as the pressure within the sealing chamber is higher than the pressure within the working 4 chamber. Even when the pressure in the sealing chamber decreases, there exists still the sealing action of the axially outer sealing ring member analogously to usual sealing systems. As compared with known sealing systems in which sealing rings have equidirectionally extending sealing lips the sealing system of the present invention has the advantage that each sealing ring is subject to a well-defined pressure difference.

For a better understanding of the invention, its operating advantages and specific objections attained by its use, reference should be had to the accompanying drawing and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the enclosed drawing a gas spring is shown which realizes the principles of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The gas string 10 as represented in the single Figure consists essentially of a containe.r tube 11 in which a piston 1V rod 12 with a piston 13 secured thereto can be driven in and out. The piston rod 12 is conducted out of the container tube 11 in a piston rod guide 14.

The container tube 11 is divided into a working chamber and a sealing chamber 16. The sealing chamber 16 is sealed off to the exterior, that is in the region of the piston rod guide 14, by an outer sealing ring member 17 and to the o odO working chamber 15 by an inner sealing ring member 18. Th 6Co outer .ealing ring member 17 comprises a radially outer, Og'o 10 inwardly pointing, sealing lip 19 which rests on the inner wall of the container tube 11. Moreover the outer sealing ring member 17 comprises a radially inner, axially inwardly pointing sealing lip 20 which rests in sealing manner on i0 the surface of the oiston rod 12.

The inner sealing ring member 18 has a .radially ouuer, axially outwardly pointing sealing lip 21 and a radially inner, axially outwardly pointing sealing lip 22. The sealinj lips 19 and 20 of the outer sealing ring member 17 and the sealing lips 21 and 22 of the inner sealing ring member 18 are arranged facing one another across the sealing chamber 16. An outer support ring 23 is arranged in the sealing chamber 16 between the outer sealing ring member 17 and the inner sealing ring member 18.

On the inner side facing away from the sealing chamber 16 the inner sealing ring member 18 is supported with an inner support ring 24 which is made fast on a corrugation The corrugation is at the same time the outer stop for the piston rod 12 and the piston 13 in outward movement.

6 1 7 The piston 13 subdivdes the working chamber 15 into partial working chambers 15a and 15b which are in communication through a throttled passage 13a. The working chamber 15 is filled with a pressurized gas. Also the sealing chamber 16 is filled with a pressurized gas.

The pressure of the pressurized gas within the sealing chamber 16 exceeds the pressure of the pressurized gas within the working chamber 15 at least after completing the gas spring and during a long-lasting early lifetime period of the gas spring. In addition to the volume of pressurized gas, both the working chamber 15 and sealing chamber 16 may contain a lubricant agent, While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise Swithout departing from such principles.

t r. i ~L i i i ;i

Claims

1. A cylinder-piston device comprising a cylindrical container having an axis and two ends and defining a cavity therein, piston rod guiding means pro- vided adjacent to at least a first one of said two ends, a piston rod member guided by said piston rod guiding means inwards and outwards of said container along 8 *o said axis of said container, sealing means adjacent to said piston rod guiding means said sealing means comprising an axially outer sealing unit and an axially inner sealing unit a sealing chamber being defined axially between said axially outer and said axially inner sealing units, both said axially outer and said axially inner sealing units com- prising a respective sealing ring member said sealing ring members being in sealing engagement with both an internal circumferential face of said container and an external circumferential face of said piston rod member, a working chamber being defined axially between said axially inner sealing unit and the second end of said container said working chamber con- tairing a volume of pressurized fluid, characterized by each of said sealing ring members having a radially outer sealing lip sealingly engaging said internal circumferential face and a radially inner sealing lip sealingly engaging said external circumferential face, 8 n. respective sealing lips of said sealing ring members extending in opposite axial directions towards said sealing chamber, said sealing chamber receiving a volume of pressurized gas, the pressure of said volume of pressurized gas within said sealing chamber exceeding the pressure.of.said pressurized fluid within said working chamber.

2. A cylinder-piston device as set forth in claim 1, at least one of said sealing ring members having an axially directed end face directed towards said sealing chamber said radially inner and said radially outer sealing lip being defined by an annular re- cess of said at least one sealing ring memboe about said axis.

3. A cylinder-piston device as set forth in claim 2, said annular recess having when regarded in a longitudinal cross-section containing said axis a substantially para- bolic contour.

4. A cylinder-piston device as set forth in one of claims 1 to 3, said sealing ring members being axially spaced by a spacer ring adjacent to said inter- nal circumferential surface. 9 Il A cylinder-piston device as set forth in one of claims 1 to 4, said axially outer sealing ring member being supported in axially outward direction by said piston rod guiding means, said.axially inner sealing ring member being axially outwardly supported by said axially outer sealing ring..member through a spacerring, and said axially inner sealing ring member being axially inwardly supported by radially inwardly directed bulge means j of said container 6, A cylinder-piston device as set forth in claim a further spacer ring being provided axially between said axially inner sealing ring member and said bulge I Smeans,. 7, A cylinder-piston device as set forth in one of claims 1'to 6, said body of fluid within said working cham- ber comprising a body of pressurized gas,

8. A cylinder-piston device as set forth in one of claims 1 to 7, said sealing chamber containing a lubri- cant agent.

9. A cylinder-piston device as set forth in one of claims 1 to 8, said working chamber containing a lubri- cant agent. 10 z- 11 A cylinder-piston device as set in claims 8 or 9, sai'd lubricant agent being a liquid cicant agent.

11. A cylinder-piston device as set forth in one of claims 1 to 10, said piston rod carrying a piston unit within said working chamber, said piston unit subdividing said working chamber into two partial working chambers, said partial working chambers being interconnected by a flow passage by passing said passage unit.

12. A cylinder-piston device as set forth in one of claims 1 to 11, said piston cylinder unit being a pneumatic spring.

13. A cylinder-piston device substantially as hereinbefore described with reference to the drawing. DATED this 9 day of January 1991 'STABILUS GMBH Patent Attorneys for the Applicant; F.B, RICE CO. I L J